Art of tanning hides



bark, wood, or herbssuch as hemlock, oak,

NITED STATES PATENT OFFICE.

THEODORE D. PALMER, OF NEYVARK, NEW JERSEY.

ART .oF TANNING HIDES.

SPECIFICATION forming part of Letters Application filed December10,1893,

To all whom, it may concern.-

Be it known that I, THEODORE D. PALMER, a citizen of the United States,residing in the city of Newark, county of Essex, and State of NewJersey, have invented a new and useful Improvement in the Art of TanningHides, of which the following is a specification.

This invention relates to the art or process of tanning hides and skinsto convert them into leather, the object being to provide a process bywhich the hides can be converted into leather in a very short space oftime at a reduced cost and at the same time have the process so arrangedthat the best results can be hadtl1at is, the finest and best grades ofleather may be produced with the least possible cost.

The process of tanning heretofore has been to immerse the hides in aliquor made from quebrachos, gambrie, or canagrie rootcontaining tannicacid as active agent and certain other substances commonly known asreds, which are found necessary in tanning. First the solution is weakand is gradually increased in strength until it is thoroughlyincorporated within the hide. Sometimes mechanical means are used toagitate the liquor, thus making it more quickly penetrate the hide; butin either case the process is very slow and. it takes about four monthsto produce anything like a properly-tanned hide. Thus a great deal ofroom and a large number of tubs and considerable handling to do a verylittle work are necessary and make the process expensive.

The reason why the liquor is so slow in penetrating the hide in theabove-described method is the fact than the tanning agents, such as thebarks and herbs above referred to, are not thoroughly dissolved and donot impart their full strength until the hides have been in the liquorfora long time. This is shown in all such solutions by a flakyappearance of the liquid caused by the undissolved particles. The methodwhich I adopt, therefore, and which not only quickens the process, butmakes better leather, is as follows: I first take the tanning liquor,which is mixed of the usual ingredients, as above described, and to thisadd a suitable clarifying agent, such as borax or other ingredientPatent No. 625,411, dated May 23, 1899.

Serial No. 699,019. (No specimens.)

having a like chemical action, in sufficient quantities to form achemical combination between the tannis, reds, and gums of the liquor,forming a solution quite clear of any undissolved particles. The hide isthen prepared by any of the well-known processes and is then immersed inthe clarified liquor. The liquor being thoroughly clarified, as abovedescribed, will penetrate the hide very quickly and produce the desiredresult in a very short space of time, probably one-tenth of the timerequired by the usual and slower method. Then the hide is thoroughlyfilled with the clarified liquor, (or has in the judgment of theoperator taken up sufficient of the tanning matter to produce the classof leather he desires to make, which will be in about five to sixdays'for upper-leather and eight to ten days for sole-leather,) it isimmersed in a bath of weak acid or other wellknown reacting agents toprecipitate again the tanning liquor in the hide and render it permanentthere. This is shown by water only, and not tan liquor, being expelledfrom the hide when being squeezed or pressed. (A weak oxalic-acid bathwith alum or salt has been found most satisfactory for this.) After thelatter process of precipitating in the hide all of the tanning materialabsorbed by it in the tanning-bath the hide is left clear without thenecessity of scouring and loss attending the same and is generallylighter and more uniform in color.

I have described above that the liquors should be entirely clear andthen that the tannings should be entirely reprecipitated in the hide;These are the points which in practice show the best results andgreatest economy, though the process is applicable when these points areonly approximately reached.

The principal advantages are saving in the tan liquor, the more rapidmanner in which the work can be done, and the effect upon the leather,which renders it of a superior grade. With my improved process anordinary fifty-pound hide can be treated in about five days and willproduce the finest grade of rough or upper leather, and the more heavysole-leather hides can be treated in about eight days, thus reducing thelabor necessary in handling and producing much better leather.

clarifying the tanning liquor, and reprecipi- I claim, and desire tosecure by Letters Patt-ating it when in the hide, substantially as setent of the United States, isforth.

1. The process herein described for tan- In testimony that I claim theforegoing I 5 5 ning leather which consists of adding asuitspecification I have hereunto set my hand able clarifying agent asherein described, to this 18th day of August, 1897.

clarify the tanning liquor and immersing the hide therein, after whichit is submitted to THEODORE PALMER an acid-bath to reprecipitate theliquor in In presence of-- lo the hide, substantially as described. 0.L. MALCOLM, 2. The art of tanning hides or skins by J. H.- BELL.

Having thus described my invention, What

